Sewage treatment device

ABSTRACT

A sewage treatment device including a macerator and pumping assembly for use with a toilet of the type utilized in recreational vehicles, such as boats, trailers, or the like. The assembly is mounted near the bottom of a toilet bowl with the macerator adjacent to the outlet of the bowl. The macerator and a pump impeller are mounted on a common shaft rotated by a motor. The impeller is mounted behind the macerator for discharging macerated sewage to waste. The macerator is an auger-like element having a point and a pair of blades formed with spiral-shaped leading edges converging toward the point. The macerator effectively macerates solid waste and conveys the same axially toward the impeller for rapid evacuation from the toilet bowl with a minimum consumption of water from the bowl.

United States Patent 11 1 Peirish, Jr. et al.

1 Apr. 22, 1975 I SEWAGE TREATMENT DEVICE [73] Assignee: InternationalTelephone and Telegraph Corporation, New York. NY.

221 Filed: May 2, I974 2| Appl. No.:466,134

Prinmry [fawnim-r-Robert l. Smith AIIUI'HC), :lgcnl. or FirmThomas L.Peterson 1571 ABSTRACT A sewage treatment device including a maceratorand pumping assembly for use with a toilet of the type utilized inrecreational vehicles, such as boats. trailers, or the like. Theassembly is mounted near the bottom of a toilet bowl with the maceratoradjacent to the outlet of the bowl. The macerator and a pump impellerare mounted on a common shaft rotated by a motor. The impeller ismounted behind the macerator for discharging macerated sewage to waste.The macerator is an auger-like element having a point and a pair ofblades formed with spiral-shaped leading edges converging toward thepoint. The macerator effectivel macerates solid waste and conveys thesame axially toward the impeller for rapid evacuation from the toiletbowl with a minimum consumption of water from the bowl.

10 Claims, 6 Drawing Figures PMENTEDAPRZZISYS sum 2 0f 5 N QE 0% QV QRfi m 1v? 0% I? 0% w QN. 1 m mm m K V SEWAGE TREATMENT DEVICE BACKGROUNDOF THE INVENTION The present invention relates generally to a sewagetreatment device and, more particularly, to a macerator and pumpingassembly for maccrating solid sewage and evacuating the same from atoilet bowl.

Toilet systems for recreational vehicles, such as boats or trailers,utilize pumping assemblies which not only evacuate the waste matter butalso supply fresh water to the toilet bowl for the flushing process. Thepumping assembly normally employs a chopper or macerator which breaks upthe solid waste prior to pumping it through the discharge line of thetoilet system. Because of its range of application and type ofinstallation, toilet systems of this type utilize volumes of freshflushing water and volumes of holding tanks for the wastes which areusually limited.

Some prior art macerator and pumping assemblies for such toilet systemshave the disadvantage that they require a substantial head of water, orwater seal, in the toilet bowl to operate properly. Without a sufficienthead of water, cavitation occurs in front of the macerator causingsolids to be propelled away from the macer ator rather than toward theimpeller behind the macer ator. This may result in the efficiency of themacerator dropping to a level of about percent. As a consequence, thereis inadequate evacuation of the waste from the toilet bowl. In addition,on occasions toilet tissue in the bowl tangles on the macerator bladescausing the opening between the macerator and the housing wall to becomeclogged or blocked thus interferring with the evacuation of waste fromthe toilet bowl.

It is, therefore, the object of the present invention to overcome theattendant disadvantages of the aforementioned prior art macerator andpumping unit for toilets by providing an assembly which effectivelymacerates waste and evacuates the same rapidly with a minimum of waterconsumption. It is also desirable that the assembly effectively shredtoilet tissue so as to prevent any clogging or blocking of the flowpassage as occurs occasionally with the prior art macerator and pumpingassembly.

SUMMARY OF THE INVENTION According to the principal aspects of thepresent invention, there is provided a macerator and pumping assemblyfor a toilet in which the macerator comprises a tapered auger-likeelement having a point and a pair of blades formed with spiral-shapedleading edges converging toward the point. The auger-like element ismounted on a shaft rotatable in a generally cylindrical housing having atubular elbow section adapted to be connected to the outlet of a toiletbowl. The macerator element is mounted adjacent to such tubular section.The waste pump impeller is mounted behind the macerator. Due to theconfiguration of the macerator blades, solid waste is effectivelymacerated and is rapidly conveyed axially toward the impeller so thatthe waste may be rapidly evacuated from the toilet bowl. Thisconfiguration of a macerator has been found not to require a large headof water as in the prior art macerator and pumping assembly discussedabove, and does not set up cavitation in front of the macerator whichresists the flow of sewage through the assembly, but instead functionsin conjunction with the swirling water currents from the toilet bowl todeliver the waste axially toward the impeller for rapid removal. Thus,water consumption by the assembly of the present invention is minimized.Also, it is desirable to provide teeth on the leading edges of theblades of the macerator element which cooperate with longitudinally andinwardly extending teeth formed on the wall of the housing of theassembly to shred toilet tissue and thus minimize if not completelyprevent the tangling of tissue on the macerator and, hence. avoidclogging or blocking of the waste flow passage. Other aspects andadvantages of the invention will become more apparent from the followingdescription taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view ofatoilet employing the improved macerator and pumping assembly of thepresent invention, with portions of the toilet wall removed to show howthe assembly is connected to the toilet components;

FIG. 2 is a partial longitudinal sectional view through the maceratorand pumping assembly illustrated in FIG. 1;

FIG. 3 is a transverse sectional view taken along line 3--3 of FIG. 2showing the teeth on the macerator element and housing therefor;

FIG. 4 is a side elevational view of the macerator element of thepresent invention, with a portion thereof shown in longitudinal section;

FIG. 5 is a front view of the macerator element illustrated in FIG. 4;and

FIG. 6 is a front end view of a modified form of the macerator elementof the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. I of thedrawings in detail, there is shown a toilet, generally designated 10,including a bowl 12, a seat 14 and a lid 16 disposed over the seat. Themacerator and pumping assembly of the invention, generally designated18, is mounted in the lower portion of the toilet housing 20 below thebowl 12. The assembly 18 comprises a generally cylindrical, horizontallydisposed housing 22 having a tubular elbow section 24 which is sealed atits upper end to the outlet 26 of the bowl 12. The right-hand end ofhousing 22 carries on electric motor (not shown) having a drive shaft 28which extends axially through the housing toward the elbow section 24,as best seen in FIG. 2. The section of the housing designated 30contains a fresh water supply pump 32. This pump comprises a rubberimpeller fixedly mounted on the shaft 28 and formed with radiallyoutwardly extending vanes 34. The housing section 30 includes an inletport 36 and an outlet portion on the opposite side of the housing, notvisible in the drawings. The inlet port 36 is connected by a line 38 toa fresh water supply, not shown. The outlet port of the pump 32 isconnected by a line 40 to an inlet 42 at the rim of the bowl 12. Thepump 32 functions to convey water from the fresh water supply to thetoilet bowl.

The housing 22 also includes an enlarged section 44 in front of pumpsection 30 in which there is mounted a sewage pump impeller 46 fixed tothe shaft 28. The macerator of the present invention, designated 48, isfixedly mounted on the shaft in front of the impeller 46. The enlargedsection 44 of the housing is formed with a discharge outlet 50. A wasteconduit 52 is connected to the outlet 50. Preferably, a check valve 54is mounted in the conduit to prevent backflow into the toilet. During aflushing operation, the macerator 48 functions to chop up or finelydivide solid waste in the sewage in the toilet 12, while the impeller 46evacuates the waste sewage from the toilet through the outlet conduit 52to waste. During the flushing operation, fresh water is supplied to theinterior of the bowl 12 by the pump 32 via the lines 38 and 40.

Referring now to FIGS. 4 and 5, the macerator 48 comprises a taperedauger-like element comprising a cylindrical shank portion 58 terminatingin a point 60 and a pair of integral blades 62 formed with spiral shapedleading edges 64 which converge toward the point 60. The shank 58 isformed with an axially extending bore 66 carrying a metal insert 68. Theshank and blades of the macerator are formed of plastic and are moldedabout the metal insert. The insert has an interfercnce fit with aforwardly extending extension 70 on the shaft 28. Preferably annularribs 72 are formed on the outer surface of the insert to assure that theplastic macerator is retained on the insert. It is noted that themacerator is mounted on shaft 28 with its point 60 facing forwardly.

It is seen that the blades 62 of the macerator element have trailingedges 70 which lie in a common plane which extends generallyperpendicular to the axis of the shank 58. The maximum distance betweenthe leading edges 64 ofthe blades (at such plane) is about twice asgreat as the distance between the plane and the point 60 of the shank.

The leading edges 64 of the blades of the auger-like macerator eiementare formed with a plurality of outwardly extending teeth 72. The section74 of the housing 22 surrounding the macerator is formed with aplurality of longitudinally and inwardly extending teeth 76, as bestseen in FIG. 3. Preferably, the teeth 76 are inclined in a directionopposite to the direction of rotation of the macerator 48, indicated bythe arrows in FIG. 3. Thus, when the macerator rotates, the teeth 72 onthe blades thereof cooperate with the teeth 76 on the housing section 74to create a shearing action on any toilet tissue which is beingevacuated from the bowl 12.

Reference is now made to FIG. 6 of the drawings which shows a modifiedform of the macerator of the present invention, generally designated48'. This macerator is identical to that described hereinbefore exceptthat the blades 64' are provided with only a single outwardly extendingprojection or tooth-like element 72' adjacent to the trailing edge 70'.The toothlike ele ments 72' will cooperate with the teeth 76 of the housing to shear toilet tissue in a similar manner to the teeth 64 on themacerator 48.

The impeller 46 behind the macerator 48 is formed with a plurality ofradially and axially extending generally flat blades 78. The impellermay employ for example, four of such blades, only two being visible inFIG. 2. Obviously, a larger or fewer number of blades may be employed ifdesired. The outlet 50 on the housing is radially aligned with theblades 78. Preferably the blades are formed with cutout sections 80adjacent to the hub 82 of the impeller which is mounted on the shaft 28.These cutout sections face in the direction of the macerator 48. Thecutout sections prevent wads of toilet tissue from becoming entangledupon the impel- [er blades which could jam the impeller and stop themotor in the assembly 18.

The macerator 48 of the present invention provides several distinctadvantages. It has been found that the auger-like configuration of themacerator sets up a flow pattern that tends to take advantage ofcavitation con ditions in front of the macerator and thus actually drawswaste from the toilet bowl into the macerator. Also, because of theauger-like configuration of the macerator element, the cross'sectionalarea of the mac erator is substantially less than that of the housingsection 74, thus providing substantial open space therebetween whichallows the waste to be pulled rapidly through the macerator. Hence, theauger-like configuration of the macerator conveys the waste axiallythrough the housing rapidly toward the impeller 46 for rapid evacuationby the impeller. Due to the ability of the macerator of the presentinvention to effectively chop up solid waste and convey it rapidly tothe impeller 46, in spite of cavitation conditions in front of theimpeller, the macerator does not require a substantial head of water tooperate efficiently, thereby resulting in minimum water consumption. Inan actual toilet constructed in accordance with the present invention,it has been found that effective flushings may be obtained with the useof only one and a half quarts of water for typical solid waste flushes.Also, as has been previously mentioned, clogging and blocking of themacerator passageway by toilet tissue is minimized, if not avoided, bythe provision of the teeth 72 on the macerator and teeth 76 on thehousing, as well as the cutout sections on the impeller blades 78.

The operation of the macerator element of the pres ent invention hasbeen compared with oth4r types of macerators and found to be far moreeffective for chopping up solid waste and evacuating the same withouthigh water consumption. Examples of such other maeerators areconventional blendertype chopper blades, circular chopper plates formedwith radially and axially extending blades thereon, and circularsegmented chopper plates with such blades. [t is seen that none of theother macerator elements which were tested embodied on auger-likeconfiguration, as the macerator of the present invention, with bladeshaving spiraLshaped leading edges converging toward a point, which isbelieved to be the primary feature of the present invention whichfacilitates effective maceration of solid waste matter and rapidevacuation thereof with minimum water consumption.

While the present invention has been described specifically for use insewage treatment, it will be appreciated that the macerator may findother useful applica tions where it is necessary to simultaneouslycomminute and convey solid material in liquid mediums, such as thickpulps, effluents containing fibrous materials, thick slurries, variouspastes, etc.

What is claimed is:

l. A device for treating sewage or the like comprising:

a housing including a generally cylindrical section and a forward sewageinlet end;

a rotatable shaft coaxially mounted within said cylindrical section;

sewage macerating and conveying means mounted on said shaft adjacent tosaid inlet end of said housing, said means comprising a taperedauger-like element having a forwardly facing point and a pair of bladesformed with spiral-shaped leading edges converging toward said point;

an impeller mounted on said shaft behind said element;

a discharge outlet on said housing in radial alignment with saidimpeller; and

means for rotating said shaft to cause said element to macerate sewageentering through said inlet end and axially convey said sewagerearwardly toward said impeller, and to cause said impeller to dischargesaid macerated sewage through said discharge outlet of said housing.

2. A device as set forth in claim 1 wherein:

said forward sewage inlet end comprises a curved, tu-

bular elbow section having a circular opening the axis of which extendsperpendicular to the longitudinal axis of said cylindrical section.

3. A device as set forth in claim 1 wherein:

an outwardly extending tooth-like element is formed on the leading edgeof each of said blades of said element.

4. A device as set forth in claim 3 wherein:

the portion of said housing surrounding said element is formed with aplurality of elongated, longitudinally and inwardly extending teeth.

5. A device as set forth in claim 4 wherein:

said leading edges of said blades are formed with a plurality of saidtooth-like elements.

6. A device as set forth in claim 4 wherein:

said teeth are inclined in a direction opposite to the direction ofrotation of said element.

7. A device as set forth in claim 1 wherein:

said impeller is formed with a plurality of axially and radiallyoutwardly extending blades, said impeller blades having cut-out sectionsadjacent to said shaft and opening toward said element.

8. A device as set forth in claim 1 wherein:

said element includes a generally cylindrical shank portion terminatingat one end in said point, said blades being integral with said shank andhaving a trailing edge lying in a common plane generally perpendicularto the axis of said shank, and the maximum distance between the leadingedges of said blades is about twice as great as the distance betweensaid plane and said point.

9. In a device for treating sewage or the like material a housing havingan inlet. a rotatable shaft in said housing, a macerator and an impellermounted on said shaft with said macerator being disposed between saidinlet and said impeller, a discharge outlet on said housing incommunication with said impeller, and means for rotating said shaft. theimprovement which comprises:

said macerator comprising a tapered auger-like element having a pointand a pair of blades formed with spiral-shaped leading edges convergingtoward said point; and

rotation of said element by said rotating means causing materialentering said housing through said inlet to be macerated and conveyedaxially toward said impeller. and pumped by said impeller outwardlythrough said discharge outlet.

10. A device as set forth in claim 9 wherein:

said blades are formed with outwardly extending teeth; and

the section of said housing surrounding said element is formed with aplurality of longitudinally and inwardly extending teeth.

* 1F il IF

1. A device for treating sewage or the like comprising: a housingincluding a generally cylindrical section and a forward sewage inletend; a rotatable shaft coaxially mounted within said cylindricalsection; sewage macerating and conveying means mounted on said shaftadjacent to said inlet end of said housing, said means comprising atapered auger-like element having a forwardly facing point and a pair ofblades formed with spiral-shaped leading edges converging toward saidpoint; an impeller mounted on said shaft behind said element; adischarge outlet on said housing in radial alignment with said impeller;and means for rotating said shaft to cause said element to maceratesewage entering through said inlet end and axially convey said sewagerearwardly toward said impeller, and to cause said impeller to dischargesaid macerated sewage through said discharge outlet of said housing. 1.A device for treating sewage or the like comprising: a housing includinga generally cylindrical section and a forward sewage inlet end; arotatable shaft coaxially mounted within said cylindrical section;sewage macerating and conveying means mounted on said shaft adjacent tosaid inlet end of said housing, said means comprising a taperedauger-like element having a forwardly facing point and a pair of bladesformed with spiral-shaped leading edges converging toward said point; animpeller mounted on said shaft behind said element; a discharge outleton said housing in radial alignment with said impeller; and means forrotating said shaft to cause said element to macerate sewage enteringthrough said inlet end and axially convey said sewage rearwardly towardsaid impeller, and to cause said impeller to discharge said maceratedsewage through said discharge outlet of said housing.
 2. A device as setforth in claim 1 wherein: said forward sewage inlet end comprises acurved, tubular elbow section having a circular opening the axis ofwhich extends perpendicular to the longitudinal axis of said cylindricalsection.
 3. A device as set forth in claim 1 wherein: an outwardlyextending tooth-like element is formed on the leading edge of each ofsaid blades of said element.
 4. A device as set forth in claim 3wherein: the portion of said housing surrounding said element is formedwith a plurality of elongated, longitudinally and inwardly extendingteeth.
 5. A device as set forth in claim 4 wherein: said leading edgesof said blades are formed with a plurality of said tooth-like elements.6. A device as set forth in claim 4 wherein: said teeth are inclined ina direction opposite to the direction of rotation of said element.
 7. Adevice as set forth in claim 1 wherein: said impeller is formed with aplurality of axially and radially outwardly extending blades, saidimpeller blades having cut-out sections adjacent to said shaft andopening toward said element.
 8. A device as set forth in claim 1wherein: said element includes a generally cylindrical shank portionterminating at one end in said point, said blades being integral withsaid shank and having a trailing edge lying in a common plane generallyperpendicular to the axis of said shank, and the maximum distancebetween the leading edges of said blades is about twice as great as thedistance between said plane and said point.
 9. In a device for treatingsewage or the like material, a housing having an inlet, a rotatableshaft in said housing, a macerator and an impeller mounted on said shaftwith said macerator being disposed between said inlet and said impeller,a discharge outlet on said housing in communication with said impeller,and means for rotating said shaft, the improvement which comprises: saidmacerator comprising a tapered auger-like element having a point and apair of blades formed with spiral-shaped leading edges converging towardsaid point; and rotation of said element by said rotating means causingmaterial entering said housing through said inlet to be macerated andconveyed axially toward said impeller, and pumped by said impelleroutwardly through said discharge outlet.